I really do hope they EM drive theorists are onto something; if it works, and depending on how well it works, the space flight applications range from replacing maneuvering thrusters to decreasing the cruising times of missions. If, by some miracle of physics, EM drives work spectacularly well, they could replace chemical rocketry for orbital insertion completely and make space access trivial.

If EM drives offer any degree of thrust, telecommunications and science missions will benefit considerably. If it's possible to supply a lot of thrust, they'll literally change the destiny of humanity. But first, we need to know if they work or not. The theories are certainly intriguing, and there are a fair few anecdotal hints that there is something there, but as the several hundred pages of the previous thread show, figuring out what's going on is a real bear.

Chris, thanks for cleaning up the old thread. There is a lot of good discussion and information in there.

EM drives would have to push or pull against something. The favorite explanation seems to be the Mach Effect, but is there any experimental evidence that points to the Mach Effect being real? Since the origin of inertia seems to be the key, what about the Higgs field? Local gravitational field?

Although I have my doubts, the potential payoff for spaceflight is so large, this should be looked into, but the experiments need to be rigorously done and repeatable.

I really do want to follow this, on the chance that it bears out. There was some good stuff on that thread, but a low s/n ratio combined with a high post count, at the long-ago point I stopped following.

Hoping this will do better. (Might even suggest you leave the old thread open to allow this one to stay cleaner, but know that wouldn't work!)

That is a very interesting paper. Very clean results compared to previous presentations and the Hoyl and Narliker approach to theory looks promising. It needs to be emphasised that this is an ME device, not EM, and that the paper reports that the theory is a work in progress.

Only had a quick look at the paper. I would like to know the positioning of the accelerometer. If this is a displacement or zero set type balance the acceleration during the constant thrust segment should be zero. Possibly the mounting accounts for this ??

Edit: OK. The "accelerometer" is between the PZT. It is not the system accelerating, just an indication that the transducers are receiving power.

That is a very interesting paper. Very clean results compared to previous presentations and the Hoyl and Narliker approach to theory looks promising. It needs to be emphasised that this is an ME device, not EM, and that the paper reports that the theory is a work in progress.

EDIT: Dimensions for Shawyer's and Brady et.al.'s cavities updated as per latest estimates on 05/20/15

Here is a comparison of reported measurements for EM Drives and for the latest report by Fearn, Zachar, Woodward & Wanser.

Notice that the force per power input reported by Fearn, Zachar, Woodward & Wanser is several orders of magnitude lower than the "EM drives". Actually it is barely (3.5 times higher) more than the force per power input of a photon rocket:

lengths in meterrfFrequency in 1/second (microwave frequency during test)power in wattsforce in milliNewtonsforce per PowerInput in milliNewtons/kWc= 299705000 m/s (speed of light in air)c= 299792458 m/s (speed of light in vacuum) (for Cannae Superconducting)(the difference between c in air compared to c in vacuum is negligible)

Here is a comparison of reported measurements for EM Drives and for the latest report by Fearn, Zachar, Woodward & Wanser.

Notice that the force per power input reported by Fearn, Zachar, Woodward & Wanser is several orders of magnitude lower than the "EM drives". Actually it is barely (3.5 times higher) more than the force per power input of a photon rocket:

lengths in meterrfFrequency in 1/second (microwave frequency during test)power in wattsforce in milliNewtonsforce per PowerInput in milliNewtons/kWc= 299705000 m/s (speed of light in air)c= 299792458 m/s (speed of light in vacuum) (for Cannae Superconducting)(the difference between c in air compared to c in vacuum is negligible)

measured ForcePerPowerInput = 80 to 243Force/PowerInput of a Photon Rocket =0.003337measured ForcePerPowerInput to the one of a photon rocket =23,980 to 72,830

All Brady cases have the following dimensions:

cavityLength=0.332;bigDiameter=0.397;smallDiameter=0.244;

(* Brady a TM mode*)rfFrequency=1.9326*10^9;

power = 16.9 Q = 7320

measured force = 0.0912measured ForcePerPowerInput = 5.396Force/PowerInput of a Photon Rocket =0.003337measured ForcePerPowerInput to the one of a photon rocket =1,617.2

(* Brady b TM mode*) rfFrequency=1.9367*10^9;

power = 16.7Q = 18100

measured force = 0.0501measured ForcePerPowerInput = 3.000Force/PowerInput of a Photon Rocket =0.003337measured ForcePerPowerInput to the one of a photon rocket =899.12

(* Brady c TE mode *)rfFrequency = 1.8804*10^9;

power = 2.6Q = 22000

measured force = 0.05541measured ForcePerPowerInput = 21.31Force/PowerInput of a Photon Rocket =0.003337measured ForcePerPowerInput to the one of a photon rocket =6,386.7

(* Fearn, Zachar, Woodward & Wanser*)rfFrequency = 39,300;

power = 170

measured force = 0.002measured ForcePerPowerInput = 0.01176Force/PowerInput of a Photon Rocket =0.003337measured ForcePerPowerInput to the one of a photon rocket = 3.526

While the force per power input is smaller, at least the ME work seems to be much furhter along. After skimming the newest paper I also noticed that there is an additional paper that was published this year focusing on the experimental results.

I'm glad to see the discussion continued in this thread. I must admit, I felt disappointed at the prospect of losing this resource and the small band of interested theorists and experimentalists exploring what may appear to be the impossible, but which may ultimately result in profound space flight applications.

Might I suggest, that if this forum turns out not to be the right place in the future (e.g., if the thread is removed again), that all those who maintain an interest in the topic to congregate in the http://www.reddit.com/r/emdrive forum. In fact, I suggest that you bookmark that page now for future reference.

I too do not appreciate personal attacks, which have no place in this kind of discussion, and so I understand the desire to keep the thread clean. On the other hand, this topic is too important not to keep alive.

Can I just thank you for providing that link as it appears to be a good source of information on this topic.

Here is a comparison of reported measurements for EM Drives and for the latest report by Fearn, Zachar, Woodward & Wanser.

Notice that the force per power input reported by Fearn, Zachar, Woodward & Wanser is several orders of magnitude lower than the "EM drives". Actually it is barely (3.5 times higher) more than the force per power input of a photon rocket:

Excellent stuff indeed, I will be perusing the previous thread in an attempt to better understand the logic. Easy enough for me to ignore the nonsense. Hoping we see more evidence from the many experiments underway to fuel the discussion. Many thanks to all the contributing members, truly a thought provoking thread.

Logged

Space is not merely a matter of life or death, it is considerably more important than that!

May I suggest that people interested in "Mach effect" (reality of which having obvious consequences on directions advanced spaceflight can take) contribute on a thread with a more appropriate explicit topic (and historical content) : Propellantless Field Propulsion and application. The risk in splitting the somewhat frozen propellantless discussion of late would be to make it even harder to revive some activity, but EM and ME approaches are two very different kind of theories and devices, interwining of both topic discussion in a single thread was one of the reason of the chaos that plagued the 1st EM drive thread.